KR20090086574A - Efficient search for wireless networks in connected mode - Google Patents

Abstract

Techniques for searching for wireless networks are described. In one scheme, a user equipment (UE) performs a manual search for detectable wireless networks while operating in a connected mode. The UE operates in the connected mode for communication with a wireless network and receives a request to search for detectable wireless networks. The UE performs a search for detectable wireless networks while operating in the connected mode, e.g., as background task during DRX time. In another scheme, the UE retains a search request received in an active state and performs a search at a later time after transitioning to an idle state. In yet another scheme, the UE efficiently handles a search across state transitions. The UE may cancel, suspend, resume, or continue the search after each transition from one state to another state based on the type of each state. ® KIPO & WIPO 2009

Description

Efficient SEARCH FOR WIRELESS NETWORKS IN CONNECTED MODE

TECHNICAL FIELD The present invention relates generally to communications, and more particularly to techniques for the discovery of wireless communication networks.

Wireless communication networks are widely deployed to provide various communication services such as voice, packet data, broadcast, messaging, and the like. These wireless networks can support communication with multiple terminals by sharing the available network resources. Examples of such wireless networks include code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal frequency division multiple access (OFDMA) networks. In addition, these wireless networks may utilize various wireless technologies, such as W-CDMA, cdma2000, and General Purpose System for Mobile Communications (GSM), which are known in the art.

Wireless devices (eg, cellular phones) are capable of communicating with various wireless networks. The wireless device may perform a search to find a wireless network from which the service can be obtained. This discovery may include (a) when the wireless device is not in a service state, such as a power-on state, (b) the wireless device is currently communicating with a wireless network that is not a high priority wireless network, or (c) It can be triggered when you want to get a list of searchable / available wireless networks. It is desirable that the wireless device perform the search as efficiently as possible so that the service can be obtained from an appropriate wireless network, is not interrupted by current communication (if present), and the user captures a good user experience.

Therefore, there is a need in the art for techniques for efficiently searching for wireless networks.

In this specification, a technique for searching for a wireless network is described. These techniques can be used for a variety of wireless networks, such as Universal Mobile Telecommunications System (UMTS) networks utilizing W-CDMA, GSM networks, and the like.

In one aspect, a user terminal (eg, cellular phone) performs a manual search for a detectable wireless network while operating in a connected mode. The UE operates in a connected mode for communication with a wireless network, eg, a UMTS network. The UE receives a discovery request for wireless networks detectable with the UE. The UE performs discovery as a background task for a detectable wireless network while operating in connected mode, for example during a discontinuous reception (DRX) time.

In another aspect, the UE keeps the discovery request in an active state and later performs discovery. The UE operates in an active state of the connected mode, for example in the CELL_DCH state or the CELL_FACH state in UMTS. The UE receives a discovery request for wireless networks and maintains the request while operating in an active state. The UE performs a search for the wireless network after switching from the active state to the idle state, such as the CELL PCH state, URA PCH state or idle mode in UMTS.

In another aspect, the UE efficiently manipulates discovery across state transitions. The UE operates in the first state and receives a discovery request for wireless networks. Thereafter, the UE switches from the first state to the second state. The UE performs a search for the wireless network in the first state, or the second state, or the first and second states, based on the type of each state. The UE may perform discovery in the first state if it is in an idle state, and continue discovery in the second state if it is in another idle state. The UE may execute discovery in the first state if it is in an idle state, and stop or cancel discovery in the second state if it is in an active state. The UE may delay the discovery in the first state if it is active and perform the discovery in the second state if it is idle.

Hereinafter, various aspects and features of the present invention will be described in more detail.

1 shows an arrangement with a UMTS network and a GSM network.

2 shows a protocol stack of UMTS and GSM.

3 shows a state and mode in UMTS and GSM in a state diagram.

4 shows a timeline for a UE in DRX mode.

5 shows an example of search processing according to state transition.

6 shows a process for performing a manual search in connected mode.

7 shows a process for manipulating a search request in an active state.

8 shows a process for manipulating a search over a state transition.

9 shows a block diagram of a user terminal UE.

The discovery techniques described herein may be used for a variety of wireless communication networks, such as UMTS networks, GSM networks, cdma2000 networks, and the like. The terms "system" and "network" here are often used interchangeably. The GSM network utilizes a GSM air interface and a mobile application part (MAP) core network. In addition, the GSM network may implement General Packet Radio Service (GPRS) or Edge (EDGE) of packet data. UMTS networks utilize wideband-CDMA (W-CDMA) air interfaces and MAP core networks. The terms "wireless interface", "wireless technology", and "wireless access technology" are used interchangeably. The terms "W-CDMA" and "UMTS may also be used interchangeably. W-CDMA and GSM are presented in the documents of the" 3rd Generation Partnership Project (3GPP). "Cdma2000 is a" 3rd Generation Partnership Project. " 2 (3GPP2) ".

In general, the wireless network may utilize any wireless technology such as W-CDMA, GSM, cdma2000, and the like. The network operator / service provider may deploy one or more wireless networks of one or more wireless technologies. For clarity, search techniques are described below for UMTS and GSM. For clarity, UMTS techniques are used a lot in the description below.

1 shows a deployment 100 comprising a UMTS network 110 and a GSM network 120. The UMTS network 110 includes a Node B 112 that communicates with a user terminal UE in the coverage area of the UMTS network. A radio network controller (RNC) 114 is coupled to Node B 112 to provide coordination and control of these Node Bs. GSM network 120 includes a Node B 122 in communication with a UE within the coverage area of the GSM network. A mobile switching center (MSC) 124 is connected to node B 122 to provide coordination and control for these node Bs. The RNC 114 may communicate with the MSC 124 to support inter-working between UMTS and GSM networks. In general, Node B is a fixed station that communicates with the UE and may also be referred to as a base station, a base transceiver station (BTS), an enhanced Node B (eNode B), an access point, and the like. Typically, a wireless network includes a number of cells, where the term “cell” may refer to a Node B, or coverage area of Node B, depending on the context in which the term is used.

The UE 150 may be capable of communicating only with the UMTS network 110 or the GSM network 120, or with both the UMTS network 110 and the GSM network 120. The UE 150 may be capable of communicating with other wireless networks, such as the cdma2000 network. The UE 150 may be a fixed terminal or a mobile terminal, and may also be called a mobile station (MS), a mobile station (ME), a terminal, a station (STA), or the like. The UE 150 may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a subscriber unit, or the like. UE 110 may communicate with one or more Node Bs on the downlink and / or uplink at any given moment. The downlink (or forward link) refers to the communication link from the Node B to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the Node B.

The UMTS network 110 and the GSM network 120 may belong to the same or different public land mobile communication network (PLMN). The PLMN may comprise one or more wireless networks, such as one or more UMTS networks and / or one or more GSM networks. The PLMN is uniquely identified by a specific mobile country code (MCC) and a specific mobile network code (MNC). For a given PLMN, the UMTS network and the GSM network may have coverage areas that may or may not overlap. In addition, multiple PLMNs may be deployed to various service providers in a given geographic area.

The UE 150 may be supplied with a list of preferred PLMNs to which the UE may be served. This preference list may be supplied by the service provider to which the UE subscribes. The preference list typically includes a home PLMN (HPLMN) with which the service provider has a roaming contract, and another PLMN. The preference list may be stored in a subscriber identity module (SIM), a universal SIM (USIM), or some other non-volatile memory module. In addition, the UE may maintain a list of PLMNs found by the UE during previous discovery. This list of PLMNs found can be stored in an acquisition database as non-volatile memory.

2 shows a protocol stack of UMTS and GSM. The UMTS protocol stack includes Non Access Stratum and Access Stratum (AS). The NAS has functions and protocols that support traffic and signaling between the UE and the core network to which the UMTS network interfaces. The AS has a function and a protocol for supporting communication between the UE and the RNC in a UMTS network. In UMTS, the AS includes a radio resource control (RRC) layer, a radio link control (RLC) layer, a media access control (MAC) layer, and a physical layer. The RRC is a layer 3 which is a partial layer. The RLC and MAC are layer 2, which is a partial layer, which is also referred to as data link layer. The physical layer is also referred to as layer (1).

Similarly, GSM includes NAS and AS. In GSM, the AS comprises a radio resource (RR) management layer of layer 3, an RLC and MAC layer of layer 2, and a physical layer of layer 1.

RRC and RR perform various functions such as searching for PLMNs, making, maintaining, and terminating calls. For simplicity, only functions related to PLMN search are described below.

3 shows a state diagram 300 of various states and modes in UMTS and GSM. For the sake of simplicity, the state diagram 300 merely represents the relevant states and modes, not all possible states and modes. When powered on, the UE performs cell selection to find a cell suitable for receiving service. This cell is called a serving cell. Then, depending on whether there is any activity for the UE and whether the UE is communicating with a UMTS network or a GSM network, the UE may be in idle mode 310, UMTS terrestrial radio access (UTRA) RRC connected mode 320, Switch to GSM connection mode 330 or GPRS packet transmission mode 340. In idle mode, the UE registers with the UMTS or GSM network, pays attention to message paging, and updates its location with the UMTS or GSM network if necessary. The UE may receive and / or transmit data with the UMTS network during the UTRA RRC connected mode, depending on its RRC state and configuration. The UE may receive and / or transmit data with the GSM network during the GSM connected mode or GPRS packet transmission mode. The UE may switch between GSM connected mode or GPRS packet transmission mode and UTRA RRC connected mode for handover between UMTS and GSM.

During the UTRA RRC connected mode, the UE may be in one of four possible RRC states: CELL_DCH state 322, CELL_FACH state 324, CELL_PCH state 326, or URA_PCH state 328, where the DCH is dedicated. A dedicated transport channel, FACH refers to a forward access channel, PCH refers to a paging channel, and URA refers to a UTRAN Registration Area. Table 1 provides a short description of the four RRC states. RRC states and modes are described in 3GPP TS 25.331 entitled "Radio Resource Control (RRC); Protpcol Specification," published June 7, 2006.

condition Explanation CELL_DCH The UE may communicate with the UMTS network for voice or data calls over a dedicated physical channel assigned to the UE. CELL_FACH The UE may exchange signaling and low rate data with the UMTS network through a common channel shared with other UEs. CELL_PCH & URA_PCH The UE regularly monitors the PCH for message paging and no transmission is allowed on the uplink.

In the CELL PCH state, the UMTS network knows the location of the UE at the cell level. The UE executes cell update by the UMTS network whenever the UE moves to a new cell. In the URA_PCH state, the UMTS network knows the location of the UE at the URA level, where URA is a cell collection. The UE performs a URA update by the UTMS whenever the UE moves to a new URA. The UE may update its location more frequently in the CELL_PCH state than in the URA_PCH state.

The UE may switch from the CELL_DCH state or the CELL_FACH state to the idle mode by (1) executing the RRC connection establishment procedure, and (2) executing the RRC connection release procedure. The UE may switch between (1) executing the rebuild procedure from the CELL_DCH state or the CELL_FACH state to another state of the UTRA RRC connected mode, and (2) another configuration of the CELL_DCH state by executing the rebuild procedure. The UMTS network may instruct the UE to be in one of four RRC states in UTRA RRC connected mode based on the activity of the UE. The attach and rebuild procedure is described in 3GPP TS 25.331.

In UMTS, the system timeline is divided into radio frames. Each radio frame has a duration of 10 milliseconds (ms) and is identified by a 12-bit system frame number (SFN). The SFN is reset to zero at a certain time, then incremented by one for each frame, and reset to zero after reaching a maximum of 4095.

4 shows a timeline 400 for a UE during DRX mode operation. The UE may operate in DRX mode during idle mode, CELL_PCH state or URA_PCH state. DRX mode is also referred to as slotted mode paging. In DRX mode, paging occasions are assigned to the UE, which is a specific radio frame in which the UE can receive pages. The paging time point for the UE is divided into time intervals called DRX cycles. The DRX period is configurable for the UE and can be in the range of 80 ms to 5.12 seconds, but typically equals 1.28 seconds. The paging time point for a UE is determined based on several parameters, such as an International Mobile Subscriber Identifier (IMSI) unique to the UE.

The UE may wake up periodically during its paging point to receive any page sent to the UE. The page is not sent to the UE outside the paging time point. Therefore, the UE may enter a sleep state for a time between its paging times if there are no other tasks to execute. The UE can power off as many circuits as possible in the idle state to save battery power.

The UE may perform manual discovery or automatic discovery to find the PLMN. The UE may perform manual discovery whenever a user requests. The purpose of the manual search is to bring the user a comprehensive list of all the PLMNs found by the UE. The UE may periodically perform automatic discovery if it is camping on at a PLMN of lower priority than the home PLMN. The purpose of the automatic search is to find a PLMN of higher priority than the serving PLMN. Each time the regular discovery timer expires, the UE may execute an automatic discovery. The timer value may be provided by a service provider. Table 2 summarizes the main attributes of manual and automatic navigation.

Manual navigation Auto detect When to run navigation Every time a user requests Regularly whenever the regular discovery timer expires and the UE is not on the highest priority PLMN. Purpose of navigation Find all PLMNs detected by the UE Find PLMNs with higher priority than serving PLMN

In addition, the UE may perform other types of discovery. For example, the UE performs a search of the PLMN stored in the acquisition database, which is called acquisition database search. The UE has appropriate information about the PLMN in the acquisition database (eg, scrambling of timing, frequency and code information). Thus, the UE is able to perform acquisition database search for a relatively short period of time. In addition, the UE may perform a capture database search prior to automatic or manual search. The UE may use the results of the acquisition database search to reduce the search space for automatic or manual search.

Thus, the PLMN search can be an automatic search, a manual search, or some other kind of search. In PLMN discovery, the UE may perform a UMTS network discovery (or UMTS discovery), a GSM network discovery (or GSM discovery), a radio network discovery of another radio technology, or a combination thereof. The particular network to search may depend on various factors such as UE communication capacity, user subscription, mode or state of the UE, and the like.

The UE may execute PLMN discovery as a background task whenever there is a request or is triggered. Foreground tasks (eg data exchange, page reception, etc.) have a high priority and are executed first. Background tasks have a lower priority, for example run when there are no foreground tasks to run. The UE may perform PLMN discovery as a background task whenever possible, to avoid or reduce interruption of the foreground task.

While in CELL_PCH state, URA_PCH state, or idle mode, the UE may perform a search for the PLMN during DRX time when the UE does not receive a page from the serving cell. To avoid missing the page, the UE may stop the PLMN discovery during its paging time point, receive the paging channel from the serving cell, and then continue with the PLMN discovery. This allows the UE to search for the PLMN with minimal page loss. In FIG. 4, one paging time point for the UE occurs between times T ₁ and T ₂ , and another paging time point for the UE occurs between times T ₃ and T ₄ . The DRX time for the UE is before time T ₁ , between times T ₂ and T ₃ , and after time T ₄ . DRX time is potentially available for PLMN search if no other tasks need to be executed. The UE may search for the PLMN during the DRX time.

While in the CELL_DCH state, the UE may search for the PLMN during the transmission gap. The UE may operate in a compression mode that provides a gap in transmission such that the UMTS network allows measurement of the UE for neighboring cells. The UE may temporarily leave the serving cell during the transmission gap to measure another cell without losing data from the serving cell. While in the CELL FACH state, the UE may search for the PLMN during reselection measurement occasions, which is a time interval in which the UE may temporarily leave the serving cell for measurement of another cell. In the CELL_DCH or CELL_FACH state, the UE may also search for the PLMN during a time period in which the UE does not expect to exchange any data and signaling with the UMTS network.

In addition, the UE may have a communication capacity for simultaneously receiving multiple cells or frequencies. For example, the UE may have multiple antennas and multiple receivers that may be used to receive receive diversity and / or multiple-input multiple-output (MIMO) transmissions. The UE uses one or more receivers to receive data, signaling, and / or pages from the serving cell, and may use one or more other receivers to search for a PLMN. This communication capability allows the UE to perform PLMN discovery at any time, in any state and mode by using a subset of available receivers. In the following description, it is assumed that the UE has one receiver.

The UE may operate for an extended time period in UTRA RRC connected mode, in particular in CELL_PCH or URA_PCH state. When the UE is in a CELL_PCH or URA_PCH state, automatic discovery may be triggered automatically (eg, due to expiration of a regular discovery timer) and / or manual discovery may be triggered by the user. Failure to perform a search in these states results in an unsatisfactory user experience. For example, if automatic discovery is not performed, the user may stay in the visited PLMN (VPLMN) for a longer period of time even when the HPLMN is available, incurring unnecessary costs for the user and / or service provider. If a manual search is not performed, the user may not get a list of available PLMNs, making it impossible to manually select a preferred PLMN.

The UE may perform PLMN discovery during UTRA RRC connected mode to improve performance and user experience. The UE processes the discovery request in various ways for various states of the UTRA RRC connected mode based on their state characteristics.

When the UE operates in the CELL_PCH or URA_PCH state, the UE accepts the discovery request and performs the PLMN discovery. The request may be for automatic discovery, manual discovery or some other kind of discovery. The UE may execute the requested PLMN search during the DRX time to avoid missing the page. The UE may preserve state information for the PLMN discovery before the paging point, and may resume the PLMN discovery using the state information preserved at the end of the paging point.

The UE may reject the auto discovery request while in the CELL_DCH or CELL_FACH state. The NAS sends an auto-discovery request to the RRC whenever the regular discovery timer expires. If the RRC rejects the auto-discovery request, the NAS reissues the request later, for example when the short timer expires. Short timers may have a shorter duration than regular search timers. For example, a short timer may be on the order of seconds, while a regular seek timer may be on the order of minutes. In this case, the rejection of the automatic search request by the RRC may adversely affect performance. Optionally, the RRC can accept and maintain the auto-discovery request during the CELL_DCH or CELL_FACH state and execute auto-discovery at the appropriate time, such as after switching to the CELL_PCH or URA_PCH state.

The UE may reject the manual discovery request during the CELL_DCH or CELL_FACH state if (a) tasks executed in the CELL_DCH or CELL_FACH state are considered more important than manual discovery, and (b) execution of the manual discovery interrupts these tasks. have. The NAS may receive a manual discovery request from the user and send the request to the RRC. If the RRC rejects the request, the NAS can resend the request when the short timer expires. Optionally, the RRC may accept the manual search request and execute the manual search later, such as after switching to the CELL PCH or URA PCH state.

During the UTRA RRC connected mode, the UE can often switch from the CELL_PCH or URA_PCH state to the CELL_DCH or CELL_FACH state to perform cell update, URA update, packet-switched attachment, and the like. The UE remains in the CELL_DCH or CELL_FACH state for a short period of time to perform cell / URA update or registration and then returns to the CELL_PCH or URA_PCH state. Since registration is transparent to the user, rejecting manual search requests and redirecting the zero PLMN to the user is a bad user experience. Thus, if the UE enters this state due to registration, the UE may accept a manual discovery request while in the CELL_DCH or CELL_FACH state. Whenever the UE switches to the CELL_PCH state, the URA_PCH state, or the idle mode, the UE may perform manual discovery. If the UE enters the CELL_DCH or CELL_FACH state, for example, for transmitting data or signaling, responding to a page, etc. due to a cause other than registration, the UE may reject the manual discovery request.

Table 3 lists the operation of the search request according to one design. As described above, even when the search request is rejected, the request can be resent after a short time.

CELL_DCH & CELL_FACH CELL_PCH & URA_PCH Auto detect Decline auto-discovery request Accepts requests for DRX time and runs auto discovery Manual navigation Upon entry into CELL_DCH or CELL_FACH due to registration, it accepts the request and delays discovery until switching to CELL_PCH, URA_PCH, or idle mode. If not, refuse the request. Accept manual requests for DRX time and execute manual discovery

The above description generally relates to the operation of a new search request. A search request can be accepted in one RRC state. PLMN discovery may or may not be initiated when the UE moves to another RRC state. Search requests and PLMN searches can be manipulated in a variety of ways due to state transitions.

The UE may temporarily move out of the CELL_PCH or URA_PCH state, sometimes due to cell reselection, uplink data transmission, location area update, routing area update, or the like. The UE may accept the discovery request while in the CELL_PCH or URA_PCH state and may be willing to perform a PLMN discovery. The UE may then switch to another RRC state, such as a CELL_FACH or CELL_DCH state. Canceling a PLMN search due to switching to another RRC state can be a bad user experience since the cause of the state transition may be transparent to the user.

The following techniques can be used for PLMN discovery. The search may be canceled after the state transition, and will not be executed unless the same search request is resent (eg, by the NAS) or another search request is sent. The search may be stopped after the state transition. A suspended search can be made to preserve its intermediate results and search status information, in which case the search can be executed later from where it was interrupted. Optionally, a paused search may cause the intermediate result and / or search status information to be deleted, in which case the search may be executed from the beginning later. Thus, a paused search can be restarted from the beginning or later when it is interrupted. In addition, the suspended search may remain suspended after the state transition. In-progress search may continue after the state transition.

For simplicity, the CELL PCH state, the URA PCH state, and the idle mode may be considered to be idle. The CELL_FACH and CELL_DCH states can be considered active. In general, the search may be canceled, stopped, resumed, or continued after switching from one state to another. Whether to cancel, stop, restart or continue the search may be, for example, whether the search was in progress or stopped before the state transition, whether the search result is still associated with after the state transition, or state transition. It can depend on a variety of factors, such as the cause of the condition and the expected length of stay in the new state.

In switching from CELL_PCH / URA_PCH to CELL_FACH, the UE may stop the automatic or manual search accepted in the CELL_PCH or URA_PCH state. The UE may temporarily stay in the CELL FACH state and then resume automatic or manual discovery upon transition to the idle state. In the transition from CELL_PCH / URA_PCH to CELL_DCH, the UE cancels automatic discovery, which can be resent by the NAS when the short timer expires. The UE may stop the manual discovery once it enters the CELL_DCH state and may resume manual discovery upon transition to the idle state. In transitioning from CELL_PCH / URA_PCH to the idle state, the UE may cancel automatic discovery since it does not need to find a high priority PLMN. The UE may start the manual search if the manual search has not been performed, or continue the search if the search is in progress.

In the transition from idle mode to CELL_FACH / CELL_DCH, the UE may cancel the auto discovery, which may be resent by the NAS. The UE may stop the manual discovery when entering the CELL_FACH / CELL_DCH state by registration, and then resume the manual discovery upon switching to the idle state. The UE may cancel the manual discovery when entering the CELL_FACH / CELL_DCH state due to reasons other than registration, and the NAS may resend the manual discovery request.

In the transition from CELL_FACH to CELL_PCH / URA_PCH, the UE may resume automatic or manual discovery if it was suspended during the CELL_FACH state. In switching from CELL FACH to idle mode, the UE may cancel the automatic discovery, which may be resent by the NAS. The UE starts (a) manual discovery if no manual discovery has been performed in any of the RRC states, (b) resumes manual discovery if manual discovery is stopped in the CELL FACH state, and (c) initiates the manual discovery. It can be canceled and it can be resent by the NAS. In switching from CELL_FACH to CELL_DCH, the UE may cancel the auto discovery and it may be resent by the NAS. The UE may stop the manual discovery during the CELL_DCH state and resume the manual discovery upon transition to the idle state.

In switching from CELL_DCH to CELL_PCH / URA_PCH / idle mode, the UE may resume manual search if manual search is stopped during the CELL_DCH state. If the automatic search is canceled when switching to the CELL_DCH state, the automatic search may not be performed. In the transition from CELL_DCH to CELL_FACH, the UE may stop the manual search during the CELL_FACH state and resume the manual search upon transition to the idle state. The UE may not auto-discover if auto-discovery is canceled due to transition to CELL_DCH state. Table 4 shows specific designs for manipulating automatic and manual search in transitions between the various states. In Table 4, "X" represents an inapplicable transition or condition.

FROM TO CELL_DCH CELL_FACH CELL_PCH & URA_PCH Idle mode Navigation type CELL_DCH X cancel cancel cancel Automatic Stop or cancel Stop or cancel Stop or cancel manual  CELL_FACH X X stop stop Automatic stop stop Stop or cancel manual CELL_PCH & URA_PCH X Restart X X Automatic Restart Restart manual Idle mode X Restart continue X Automatic Restart Restart continue manual

In the design shown in Table 4, automatic discovery is (a) canceled upon transition to the CELL_DCH state and can be resent by the NAS, and (b) stopped on transition from the idle state to the CELL_FACH state. The manual search can be stopped upon (a) transitioning from an idle state to an active state by registration, and (b) canceled if the transition is due to reasons other than registration. The passive search may remain stopped due to the transition from one active state to another. The search may continue or resume upon transition to the idle state.

In the above, some example designs have been described for the operation of searching through state switching. In general, the search can be manipulated in any manner for each of the possible state transitions based on the desired outcome.

The UE may occasionally switch to the CELL_FACH or CELL_DCH state to perform registration such as cell reselection, location area update, routing area update, and the like. It may be desirable not to cancel discovery every time the UE switches to CELL_FACH or CELL_DCH state for registration. By doing so, it is possible to prevent the search from being completed due to frequency switching to CELL_FACH or CELL_DCH for registration. In addition, in cases transparent to the user, it may be desirable not to cancel the manual search, for example in the transition from CELL PCH / URA PCH to CELL FACH for cell / URA update due to reselection. The user may not be aware of these cases and may not want the manual search to end.

5 shows an example of processing for searching in a state transition. At time T _a , the UE receives a discovery request while in an idle state, which may be CELL_PCH, URA_PCH, or idle mode. The UE initiates discovery at time T _b . At time T _c , the UE transitions from an idle state to an active state, which may be CELL_DCH or CELL_FACH, and stops or cancels the discovery. At time T _d , the UE transitions to the idle state and restarts the discovery if the discovery is not canceled. At time T _e , the UE switches to another idle state and continues the discovery. At time T _f , the UE completes the discovery and provides a discovery result. In addition, the UE may perform discovery in other ways.

The PLMN may operate in one or more frequency bands. Each frequency band may cover multiple UMTS channels that may be spaced about 5 MHz apart. Each UMTS channel has a center frequency and a bandwidth of 3.84 MHz with 200 KHz resolution. Each UMTS channel is identified by a specific number of channels, which may be UARFCN (UTRA Absolute Radio Frequency Channel Number). UARFCN in various frequency bands is given in 3GPP TS 25.101, entitled "User Equipment (UE) radio transmission and reception (FDD)" published March 7, 2006. UMTS networks in a PLMN typically operate on one or more specific UARFCNs.

The UE may perform manual discovery in various ways. For example, the UE may perform manual discovery in a given frequency band as follows.

Perform a coarse frequency scan across the entire frequency band, measure the received power at low density frequencies spaced by Δfc (eg Δfc = 2 MHz), and identify strong low density frequencies.

• Perform a fine frequency scan over the UARFCN range around each strong low density frequency and identify the strong UARFCN.

Attempt acquisition on each strong UARFCN,

For example, the PLMN ID of each found PLMN is obtained by reading a Master Information Block (MIB) broadcast by a cell of the PLMN.

In addition, the UE performs automatic discovery in various ways. For example, the UE may perform auto discovery in a given frequency band as follows.

Perform a low density frequency scan to identify strong low density frequencies

Perform a fine frequency scan to identify the strong UARFCN,

Attempts to capture on each strong UARFCN

Obtain system information for the high priority cell found, for example, by reading the MIB and System Information Block Type 1 (SIBI1) and System Information Block Type 3 (SIBI3) broadcasts by the PLMN's cells.

The search can be performed in different ways for other wireless networks and wireless technologies.

6 shows a process 600 for performing a manual search in connected mode. The UE operates in connected mode for communication with the wireless network (block 612). The UE may operate in an RRC connection mode for communication with a UMTS network, a GSM connection mode for communication with a GSM network or a GPRS packet transmission mode, or any other connection mode for communication with other types of wireless networks. The UE receives a discovery request for a wireless network (PLMN) detectable by the UE (block 614). The UE performs a search for the detectable wireless network while in the connected mode (block 616). For UMTS, the UE can receive the request while in the CELL_PCH or URA_PCH state and execute the discovery while in the CELL_PCH or URA_PCH state. The UE may also receive the request while in the CELL_DCH or CELL_FACH state and perform the discovery after switching to the CELL_PCH or URA_PCH state. The UE may execute the discovery as a background task during the DRX time for the UE.

7 shows a process 700 for manipulating a search request in an active state. The UE operates in the active state of the connected mode, eg, CELL_DCH or CELL_FACH state in UMTS (block 712). The UE receives a search request for a high priority or detectable wireless network (block 714). The UE maintains the request while in the active state (block 716). The UE performs a search for the wireless network after switching from the active state to the idle state, such as the CELL_PCH state, URA_PCH state or idle mode of the UMTS (block 716).

8 shows a process 800 for manipulating a search over a state transition. The UE operates in the first state (block 812). The UE receives 814 a discovery request for a high priority or detectable wireless network while in the first state. The UE transitions from the first state to the second state (block 816). The UE performs a search for the wireless network in the first state, or the second state, or both the first state and the second state based on the type of each state.

The UE will perform discovery in the first state if it is idle and continue searching in the second state if it is another idle state. The UE may perform discovery in the first state if it is idle and stop or cancel discovery in the second state if it is active. The UE transitions from the second state to the third state and may resume discovery in the third state if it is idle and the discovery has not been canceled. The UE may delay discovery in the first state if active and execute discovery in the second state if idle.

In UMTS, the UE may perform discovery in the first state if it is one of a plurality of idle states including a CELL_PCH state, a URA_PCH state, and an idle mode. The UE may delay discovery in the first state if it is one of a plurality of active states including a CELL_DCH state and a CELL_FACH state. The UE may perform discovery in the second state if it is idle and stop discovery in the second state if it is active. For example, the UE may perform discovery in the first state, which may be in the CELL_PCH or URA_PCH state. The UE may stop the discovery in the second state, which may be a CELL_FACH or CELL_DCH state if the transition to the second state is triggered by registration, and may cancel the discovery in the second state if the transition is not triggered by registration. .

9 shows a block diagram of a UE 150 design. On the uplink, data and signaling to be transmitted by the UE 150 are processed (eg, formatted, encoded and interleaved) by the encoder 922 in accordance with applicable wireless technology (eg, W-CDMA, GSM, or cdma2000). And processed (eg, modulated, channelized and scrambled) by modulator (Mod) 924 to produce an output chip. Transmitter (TMTR) 932 then adjusts (eg, converts to analog, filters, amplifies, and frequency upconverts) the state of the output chip to generate an uplink signal transmitted via antenna 934.

On the downlink, antenna 934 receives the downlink signal transmitted by Node B and provides the received signal. Receiver (RCVR) 936 adjusts (eg, filters, amplifies, frequency downconverts and digitizes) the state of the received signal to provide a sample. Demodulator (Demod) 926 processes (eg, descrambles, channelizes, and demodulates) the sample to provide symbol estimates. Decoder 928 further processes (eg, deinterleaves and decodes) the symbol estimates to provide decoded data. Encoder 922, modulator 924, demodulator 926, and decoder 928 may be implemented by modem processor 920. These units perform processing in accordance with the radio technology (eg, W-CDMA, GSM, or cdma2000) used by the serving wireless network. For example, in W-CDMA, the demodulator 926 may perform descrambling by a scrambling sequence, despreading by an orthogonal variable spreading factor (OVSF) code, data demodulation, and the like. Demodulator 926 may perform matched filtering and equalization in GSM.

The controller / processor 940 controls the operation at the UE 150. The memory 942 stores data and program code of the UE 150. The controller / processor 940 may implement process 600 in FIG. 6, process 700 in FIG. 7, process 800 in FIG. 8, and / or other processes. The controller / processor 940 may determine whether to accept the search request, when to run the PLMN search, and the like. The controller / processor 940 may implement a timer to determine the DRX time for the UE, when to execute the automatic discovery, when to resend the discovery request, and the like. Controller / processor 940 and / or memory 942 may store state information for the in-process discovery and / or state information for the serving cell. The memory 942 may store PLMN information, acquisition databases, search results, and the like.

For simplicity, search techniques have been described in detail for UMTS and GSM. These techniques can also be used for other wireless networks such as cdma2000 networks, wireless local area networks (WLANs), and the like. The technology may be used as any number of radio technologies, such as UMTS, GSM, UMTS and GSM, UMTS and cdma2000, or any other combination of radio technologies.

The search technique here can be implemented by various means. For example, these techniques may be implemented in hardware, firmware, software, or a combination thereof. In a hardware implementation, the processing unit used to perform the search may include one or more application specific semiconductor integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gates. It may be implemented in an array (FPGA), processor, controller, microcontroller, microprocessor, electronic device, other electronic unit designed to perform the functions described herein, or a combination thereof.

An apparatus that implements the techniques described herein may be a stand-alone unit or part of a device. The device may comprise (i) a standalone integrated circuit (IC), (ii) one or more IC sets, which may include a memory IC for storing data and / or instructions, (iii) an ASIC, such as a mobile station modem (MSM), (iv) A module that can be embedded in another device, (v) a cellular phone, a wireless device, a handset, or a mobile unit, (vi), or the like.

In firmware and / or software implementations, the search technique may be implemented by modules (eg, procedures, functions, etc.) that perform the functions described herein. Firmware and / or software code may be stored in a memory (eg, memory 942 in FIG. 9) and executed by a processor (eg, processor 940). The memory may be implemented within the processor or external to the processor.

The foregoing description of the specification is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these inventions will be apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. . Thus, the present invention should not be limited to the embodiments disclosed herein, but should be construed in the broadest scope consistent with the principles and novel features disclosed herein.

Claims (34)

A processor operating in a connected mode for communicating with a wireless network, receiving a search request for detectable wireless networks, and performing a search for detectable wireless networks while operating in the connected mode; And A memory coupled to the processor, Device. The method of claim 1, And the processor executes the search as a background task during a discontinuous reception (DRX) time. The method of claim 1, And the processor operates in a radio resource control (RRC) connected mode for communication with a Universal Mobile Telecommunications System (UMTS) network. The method of claim 3, And the processor receives a search request for detectable wireless networks while in the CELL_PCH state or the URA_PCH state of the RRC connected mode, and executes the search while in the CELL_PCH or URA_PCH state. The method of claim 3, The processor receiving a discovery request for detectable wireless networks while in a CELL_DCH state or a CELL_FACH state in the RRC connected mode and executing the search after switching to the CELL_PCH state or URA_PCH state in the RRC connected mode . The method of claim 1, And the processor operates in a GSM connected mode or a General Packet Radio Service (GPRS) packet transfer mode for communication with a Global System for Mobile Communications (GSM) network. The method of claim 1, Wherein the processor receives a search request for a detectable public land mobile communication network (PLMN) and executes a search for the detectable PLMNs. Operating in a connected mode for communicating with a wireless network; Receiving a search request for detectable wireless networks; And Performing a search for detectable wireless networks while operating in the connected mode; Way. The method of claim 8, Executing the search comprises executing the search as a background task during a discontinuous reception (DRX) time. The method of claim 8, Receiving the request and executing the search comprises: receiving a search request for detectable wireless networks while in a CELL_PCH state or a URA_PCH state in a Universal Mobile Telecommunications System (UMTS); And Executing the search while in the CELL_PCH or URA_PCH state. Means for operating in a connected mode for communicating with a wireless network; Means for receiving a search request for detectable wireless networks; And Means for performing a search for detectable wireless networks while operating in the connected mode; Device. The method of claim 11, Means for receiving the request, and means for performing the search, Means for receiving a search request for detectable wireless networks while in a CELL_PCH state or a URA_PCH state in a universal mobile communication system (UMTS), and Means for performing the search while in a CELL_PCH or URA_PCH state. A processor readable medium, Instructions operable to operate in a connected mode for communicating with a wireless network; Instructions operable to receive a search request for detectable wireless networks; And Storing instructions operable to perform a search for detectable wireless networks while operating in the connected mode; Processor Readable Media. The method of claim 13, Instructions operable to receive a search request for detectable wireless networks while in a CELL_PCH state or a URA_PCH state in a universal mobile communication system (UMTS); And Further storing instructions operable to perform the search while in a CELL_PCH or URA_PCH state. Operate in an active state of a connected mode, receive a search request for wireless networks, maintain the request while operating in the active state, and after switching from the active state to an idle state A processor that performs a search for networks; And A memory coupled to the processor, Device. The method of claim 15, The active state is a CELL_DCH state or a CELL_FACH state in a universal mobile communication system (UMTS), and the idle state is a CELL_PCH state, URA_PCH state, or idle mode in UMTS. Device. The method of claim 15, And the request is for high priority wireless networks or detectable wireless networks. Operating in a first state, receiving a search request for wireless networks while operating in the first state, transitioning from the first state to a second state, based on the type of each state, the first state and the second state A processor that performs a search for wireless networks in at least one of the states; And A memory coupled to the processor, Device. The method of claim 18, And the processor executes the search in the first state if the first state is idle and continues the search in the second state if the second state is another idle state. The method of claim 18, And the processor executes the search in the first state if the first state is idle and stops the search in the second state if the second state is active. The method of claim 20, The processor transitions from the second state to a third state and resumes searching in the third state if the third state is idle. The method of claim 18, Wherein the processor executes a search in the first state if the first state is idle and cancels the search if the second state is active and a transition to the second state is not triggered by registration. . The method of claim 18, And the processor delays the search in the first state if the first state is active and executes the search in the second state if the second state is idle. The method of claim 18, The processor executes the search in the first state if the first state is any one of a plurality of idle states including a CELL_PCH state, a URA_PCH state, and an idle mode of a universal mobile communication system (UMTS), and the first state. And delay the search at the first state if the state is any one of a plurality of active states including a CELL_DCH state and a CELL_FACH state of UMTS. The method of claim 24, The processor executes the search in the second state if the second state is any one of the plurality of idle states, and performs the search in the second state if the second state is any one of the plurality of active states. Stopping device. The method of claim 18, The first state is a CELL_PCH state or a URA_PCH state of a universal mobile communication system (UMTS), the second state is a CELL_FACH state or CELL_DCH state in UMTS, and the processor executes the search in the first state, and the first state. Stop the search in the second state if a transition to a two state is triggered by registration, and cancel the search in the second state if the transition is not triggered by a registration. The method of claim 18, And the request is for high priority wireless networks or detectable wireless networks. Operating in a first state, Receiving a search request for wireless networks while operating in the first state; Transitioning from the first state to a second state, and Performing a search for wireless networks in at least one of the first state and the second state based on the type of each state. The method of claim 28, Executing the search comprises: executing the search in the first state if the first state is idle, and stopping the search in the second state if the second state is active. How to. The method of claim 28, Executing the search comprises delaying the search in the first state if the first state is active and executing the search in the second state if the second state is idle. How to. A processor readable medium, Instructions operable to operate in a first state; Instructions operable to receive a search request for wireless networks while operating in the first state; Instructions operable to transition from the first state to a second state; And Storing instructions operable to perform a search for wireless networks in at least one of the first state and the second state based on each type of state, Processor Readable Media. The method of claim 31, wherein Instructions operable to execute the search in the first state if the first state is idle; And Further storing instructions operable to stop the search in the second state if the second state is active. The method of claim 31, wherein Instructions operable to delay the search in the first state if the first state is active; And Further storing instructions operable to perform the search in the second state if the second state is idle. Operating in a first state, receiving a search request for wireless networks while operating in the first state, performing a search for wireless networks if the first state is idle, and the first state is active And delays the search, transitions from the first state to a second state, stops the search if started in the first state and the second state is active, and does not start in the first state. A processor configured to execute the search if the state 2 is idle; And A memory coupled to the processor, Device.

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